Sorry to resurrect this, but do they check expiration dates? I'm running paintball co2 and my tank is expired...Topps Liquors in Tempe. Dollar per pound. They refill your tank and don't exchange it for whatever they have. Awesome. Only place I've ever gone to. From what I've read, most other places are considerably more expensive and might give you a crappy looking tank in exchange for the nice one you may have bought.